The present invention relates to screen printing machines in general, and more particularly to improved mounting and biasing means for a squeegee which is installed in the interior of a cylindrical or band-like stencil in a screen printing machine.
It is already known to mount a blade-like or rod-like squeegee in a holder which is biased in a direction toward the internal surface of the stencil by a gas-filled cushion. As a rule, the cushion consists of rubber or rubber-like synthetic plastic material so that it can undergo deformation as well as expansion and contraction. This affects the uniformity of pressure which the cushion transmits to the holder because the length of the cushion changes with changes in the pressure of entrapped fluid. Furthermore, the cushion is subjected to considerable wear because it slides along the adjacent surfaces of the holder and the carrier means whenever it expands or contracts. If the cushion cannot slide relative to the adjacent parts, the pressure in its interior varies due to varying thickness of its wall which also affects the quality of the printing operation, especially as regards the uniformity of pressure with which the squeegee is urged against the internal surface of the stencil.